Purification, crystallization and preliminary X-ray analysis of the regulatory subunit of aspartate kinase from Thermus thermophilus.

Aspartate kinase (AK) from Thermus thermophilus, which catalyzes the first step of threonine and methionine biosynthesis, is regulated via feedback inhibition by the end product threonine. To elucidate the mechanism of regulation of AK, the regulatory subunit (the beta subunit of T. thermophilus AK) was crystallized in the presence of the inhibitor threonine. Diffraction data were collected to 2.15 A at a synchrotron source. The crystal belongs to the cubic space group P4(3)32 or P4(1)32, with unit-cell parameters a = b = c = 141.8 A.